52 research outputs found
Ventilation loss and pressurization in the NASA launch/entry suit: Potential for heat stress
The potential of the NASA Launch/Entry Suit (LES) for producing heat stress in a simulated Space Shuttle cabin environment was studied. The testing was designed to identify potential heat stress hazards if the LES were pressurized or if ventilation were lost. Conditions were designed to simulate an extreme pre-launch situation with chamber temperatures maintained at dry bulb temperature = 27.2 +/- 0.1 C, globe temperature = 27.3 +/- 0.1 C, and wet bulb temperature = 21.1 +/- 0.3 C. Two females and two males, 23 to 34 years of age, were employed in this study, with two subjects having exposures in all 3 conditions. Test durations in the ventilated (V) and unventilated (UV) conditions were designed for 480 minutes, which all subjects achieved. Pressurized runs (Pr) were designed for 45 minutes, which all subjects also achieved. While some significant differences related to experimental conditions were noted in rectal and mean skin temperatures, evaporation rates, sweat rates, and heart rate, these differences were not thought to be physiologically significant. The results indicate that the LES garment, in either the Pr or UV state, poses no danger of inducing unacceptable heat stress under the conditions expected within the Space Shuttle cabin during launch or reentry
Control of Mooij correlations at the nanoscale in the disordered metallic Ta - nanoisland FeNi multilayers
Localisation phenomena in highly disordered metals close to the extreme
conditions determined by the Mott-Ioffe-Regel (MIR) limit when the electron
mean free path is approximately equal to the interatomic distance is a
challenging problem. Here, to shed light on these localisation phenomena, we
studied the dc transport and optical conductivity properties of nanoscaled
multilayered films composed of disordered metallic Ta and magnetic FeNi
nanoisland layers, where ferromagnetic FeNi nanoislands have giant magnetic
moments of 10^3-10^5 Bohr magnetons (\mu_B). In these multilayered structures,
FeNi nanoisland giant magnetic moments are interacting due to the indirect
exchange forces acting via the Ta electron subsystem. We discovered that the
localisation phenomena in the disordered Ta layer lead to a decrease in the
Drude contribution of free charge carriers and the appearance of the low-energy
electronic excitations in the 1-2 eV spectral range characteristic of
electronic correlations, which may accompany the formation of electronic
inhomogeneities. From the consistent results of the dc transport and optical
studies we found that with an increase in the FeNi layer thickness across the
percolation threshold evolution from the superferromagnetic to ferromagnetic
behaviour within the FeNi layer leads to the delocalisation of Ta electrons
from the associated localised electronic states. On the contrary, we discovered
that when the FeNi layer is discontinuous and represented by randomly
distributed superparamagnetic FeNi nanoislands, the Ta layer normalized dc
conductivity falls down below the MIR limit by about 60%. The discovered effect
leading to the dc conductivity fall below the MIR limit can be associated with
non-ergodicity and purely quantum (many-body) localisation phenomena, which
need to be challenged further.Comment: 29 pages, 8 figures. This is a post-peer-review, precopyedit version
of an article published in Scientific Reports. The final authenticated
version is available online at http://dx.doi.org/10.1038/s41598-020-78185-
Hemotin, a regulator of phagocytosis encoded by a small ORF and xonserved across metazoans
Translation of hundreds of small ORFs (smORFs) of less than 100 amino acids has recently been revealed in vertebrates and Drosophila. Some of these peptides have essential and conserved cellular functions. In Drosophila, we have predicted a particular smORF class encoding ~80 aa hydrophobic peptides, which may function in membranes and cell organelles. Here, we characterise hemotin, a gene encoding an 88aa transmembrane smORF peptide localised to early endosomes in Drosophila macrophages. hemotin regulates endosomal maturation during phagocytosis by repressing the cooperation of 14-3-3ζ with specific phosphatidylinositol (PI) enzymes. hemotin mutants accumulate undigested phagocytic material inside enlarged endo-lysosomes and as a result, hemotin mutants have reduced ability to fight bacteria, and hence, have severely reduced life span and resistance to infections. We identify Stannin, a peptide involved in organometallic toxicity, as the Hemotin functional homologue in vertebrates, showing that this novel regulator of phagocytic processing is widely conserved, emphasizing the significance of smORF peptides in cell biology and disease
Optics of epitaxial strained strontium titanate films
Abstract
Diverse effects of lattice strain on the optical properties in the near-infrared to vacuum ultraviolet spectral range are experimentally revealed in cube-on-cube-type epitaxial perovskite SrTiO3 films grown on compressive substrate. Compared to the reference crystal, the tetragonal antiferrodistortive film exhibits spectral blueshifts, which are consistent with the theoretically predicted bandgap widening. In addition to this strain-induced interband effect, the peculiar near-edge absorption and smearing of interband transitions are found. It is shown that Fröhlich-type electron–phonon coupling can be enhanced by strain and lead to this behavior. It is suggested that electron–phonon interactions can play an important role in optical properties of ferroelectric films and deserve further studies
Spectral luminescence properties of transparent lead fluoride nanoglassceramics doped with erbium ions
Photoluminescence of Perovskite Nanosheets Prepared by Exfoliation of Layered Oxides, K 2
- …